Rotary Control Valves are used extensively in various process control applications. A shaft is typically fixed to a controlling member using a tapered pin or key inserted perpendicular to the centerline of the shaft. It is desirable in control valve applications to have a shaft connection that does not allow any hysteresis. For tapered pin type connections, the shaft and controlling member must be assembled as a matched set. A tapered reamer is used to machine the correct size of taper to match the taper pin. During assembly, the tapered pin is forcibly inserted into the tapered hole and effectively wedged in place. A tapered key uses a tapered flat surface machined longitudinally onto a round bar creating a half round tapered pin. Assembly of the shaft to the controlling member requires the key to be forcibly inserted and effectively wedged in place. Both designs rely on the wedging effect of the key or pin to stay in place. U.S. Pat. No. 4,768,750 (Wilson) entitled “Valve joint connection” is an example of a ball valve that uses a tapered wedge to lock the shaft to the valve member. It is not uncommon for these types of wedged pins to come loose when subjected to repeated cycles especially when torques are higher